FIG 2.

The bacteriophage nucleus-like shell combats antiphage defense mechanisms. Jumbo phages assemble a proteinaceous shell that separates phage genomes from the bacterial cytoplasm and segregates proteins according to function during viral replication. DNA replication and transcription occur inside the shell, while translation and metabolic processes take place in the cytoplasm. The shell physically shields phage genomes from attack by DNA-targeting CRISPR-Cas systems and restriction enzymes. However, RNA-targeting CRISPR-Cas systems can cleave phage transcripts in the cytoplasm. It remains unknown how phage DNA is protected upon injection (depicted as a dashed curve and a question mark).